Fuel injection system for internal combustion engine



Sept. 16, 1958 H. E. J. PRINGHAM 2,852,011

FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINE Filed Nov. 13, 19562 Sheets-Sheet 1 INVENTOR Sept. 16, 1958 E. J. PRINGHAM I 2,352,011

,FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINE Filed Nov. 13,1956 I 2 Shets-Sheef. 2

United States l atent i FUEL INJECTION SYSTEM FOR COMBUSTION ENGINEHenry E. J. Pringham, Grosse Pointe, Mich., assignor toStudebaker-Packard Corporation, South Bend, ind, a corporation ofMichigan Application November 13, 1956, Serial No. 621,693

6 Claims. (Cl. 123.119)

This invention relates to fuel injection systems for internal combustionengines andparticularly for gasoline .engines.

.Fuel'injection systems of the type to which the present inventionpertains essentially include 1) a liquid fuel pump, (2) a liquid fueldistributor adapted to receive liquid fuel under pressure from the pumpand effect the delivery of metered charges of the fuel to .thecombustion chambers of .the engine, and (3) control means responsive tothe pressure and temperature of the mass of air flowing in the intakemanifold for controlling the metering of the fuel distributor.

A fuel distributor which may be utilized in connection with the presentinvention is known as :the shuttle or 'free piston type although broadlythe invention may also be utilized with other types of fueldistributors. In the shuttle type of fuel distributor a rotating sleeveis driven at camshaft speed and a shuttle or free piston in the sleeveis forced to reciprocate between a fixed stop and a stop which isaxially movable in the sleeve. The distance between the fixed andmovable stops determines the travel of the shuttle and concomitantlydetermines the quantities of the metered charges of liquid fueldelivered by the distributor. The .position .of the axially movable stopis varied continuously by distributor control means which are responsiveto engine conditions .including the pressure and temperature of the massof air flowing in the engine intake manifold.

It is a main object of the invention to provide a fuel injection systemhaving new and improved control means for varying in accordance withengine conditions the quantities of metered fuel charges delivered bythe fuel distributor to the combustion chambers of the engine.

Other objects of the invention will become apparent from the followingspecification, the drawings relating thereto, and the appended claims.

In the drawing:

Fig. 1 shows a diagrammatic, vertical sectional view :of a fuelinjection system embodying the invention and a fragmentary sectionalview of an internal combustion engine to which it is applied;

:Figs. 2, 3 .and 4 are sectional views :taken respectively on lines11-11, HI III and IV-IV of Fig. '1'; .and

Fig. 5 is an-enlargedrfragmentary viewofacone type of cam member shownin ,Fig. 1.

.In the drawing there is illustrated a .gasoline .injection system foran automotive type internal combustion engine. In general there is shownone of the engine :air intake conduits which is formed partly by intake:manifold .11 .and engine head 12. A combustion chamber 13 is providedin head 12 and an intake valve 14 is provided to control the admissionof air from air intake conduit 10 to combustion chamber 13. A throttlevalve 15 is pivotally mounted in manifold 11 for varying the flow of airin the manifold. Throttle valve 15 maybe controlled by an acceleratorpedal (not shown) 'to which it maybe attached by suitable linkage.

Metered charges of liquid fuel are supplied to the 2,852,01 l PatentedSept. 16, 1958 combustion chambers of the engine, including combustionchamber 13, by a liquid fuel distributor 20. 'The illustrated section ofdistributor 20 in Fig. 1 is taken on line I-I of Fig. 2. Distributor 20receives liquid fuel under pressure from a liquid fuel pump 21 andeffects delivery of metered charges of the fuel in timed relation toinjection nozzles which service "the respective combustion chambers suchas to injection nozzle 22 which services combustion chamber 13.Injection nozzle 22 may be mounted in combustion chamber 13 if desiredor on the upstream side of intake valve 14 as illustrated.

A control mechanism 23 is provided for controlling fuel distributor 20.Control mechanism 23 functions to effect varying of the quantities ofthe metered charges delivered by distributor 20 in accordance withcertain engine conditions.

Fuel pump 21 is an engine or electric motor driven, conventional geartype pump which draws liquid fuel through an inlet pipe 28 from a sourcewhich is not shown and delivers liquid fuel under pressure to fueldistributor 20 through a pipe 29. The pressure of the fuel received bydistributor 20 may been the order of 100 p. s. i. for example.

Fuel distributor 20 comprises a stationary casing 33 having alongitudinally extending bore in which a stationary :sleeve 34 isdisposed. A rotatable sleeve member 35 is rotatably disposed in thelongitudinal bore of stationary sleeve 34. Slidably disposed in thelongitudinal bore of rotatable sleeve 35 is a reciprocatable shuttle orfree :piston 36. A stop member 37 has a cylindrically shaped portionthereof disposed in the longitudinal bore of rotatable sleeve 35 on oneside of shut itle36 and in axially fixed relation to sleeve 35. A re-.ciprocatablestop member-38 having a cylindric'ally shaped portiondisposed in the longitudinal bore of rotatable sleeve 35 .in slidablerelation thereto is disposed on the other side of shuttle 36. The axialposition of recipro- -catable stop member 38 relative to rotatablesleeve '35 .is controlled by control mechanism 23 and stop member 38.functions as metering adjusting means for vary ing the quantities .ofthe metered charges delivered by distributor 20 to the combustionchambers of the engine.

Stop members 3.7 and 38 are provided with cylindrically shaped abutments39 and 40 which are smaller in diameter thanthe longitudinal bore ofrotatable sleeve 35. It is the abutments 39 and 40 of the stop membersthat shuttle 36 contacts at each end of its stroke.

Rotatable sleeve 35 is driven by the engine at onehalf crankshaftspeedfor a 4-stroke engine and at crankshaft speed for .a one strokeengine through two skew gears 42 :and 43.

Distributor casing 33 is provided with a radial port 46 through whichfuel under pressure is delivered to the distributor 20 from fuel pump.21. Eight radial delivery ports 47 to '54 are formed jointly in casing'33 and stationary sleeve 34, as indicated in Figs. 2 and 4, to whichpipes such as pipes 55 and 56 are connected for delivering metered fuelrespectively to the eight combustion chambers of an eight cylinderengine. -A set of four of the radial delivery ports 47 to 54 are on eachside of radial inlet port 46 in the planes of section lines II-II andIV--IV with the four ports in each set being spaced apart Each of thefour ports in one set is in circumferential alignment with a port in theother set such as port 47 being circumferentially aligned 'with port 51.

.Eight radial feeder ports 63 to 70 are formed in stationary sleeve 34with a set offour feeder ports 63 to 66 being in the plane of sectionline 11-11 and a set of four feeder ports 67 to 70 being in the plane ofsection line IV-lV. Feeder ports 63 to 66 are spaced 90 sleeve 34 in theplane of section line Ill--1II. Stationary sleeve 34 is provided withfour flat surface portions on the. periphery thereof which extendaxially in opposite directions from annular groove 72. of the flatsurface portions extend axially between two circumferentially alignedfeeder ports 63 to 70 to form chambers 73 to 76. Each of the chambers 73to 76 has communication with two circumferential feeder ports which thechamber services such as the servicing of feeder ports 64 and 68 bychamber 74. v

Rotatable sleeve 35 is provided with two radial ports 77 and 78 whichare circumferentially displaced 45 from each other with port 77 beingaxially aligned with feeder ports 63 to 66 and delivery ports 47 to 50in the plane of section line Illl and port 78 being axially aligned withfeeder ports 67 to 70 and delivery ports 51 to 54 in the plane ofsection line IV-IV.

Although distributor 20 as described above is adapted for use with aneight cylinder engine, it'will be understood that only routine designchanges would be required to adapt the distributor for use with engineshaving more or less cylinders.

In the operation of distributor 20 liquid fuel under pressure isreceived through fuel inlet port 46 from fuel pump 21. Fuel from inletport 46 flows through annular groove 72 of stationary sleeve 34 tochambers 73 to 76, which cross groove 72 at four circumferentiallyspaced points, to the eight feeder ports 63 to 70 in stationary sleeve34 Where the fuel is maintained under pressure. When the port 78 inrotatable sleeve 35 registers with one of the feeder ports such as port70, the other port 77 in sleeve 35 registers with one of the deliveryports such as port 47 which has direct communication through conduit 55with an injection nozzle 22 associated with one of the cylinders of theengine. Assuming that the shuttle 36 is abutting adjustable stop member38 and that delivery port 47 and conduit 55 are filled with liquid fuel,the pressurized fuel in chamber 76 Will force shuttle 36 againststationary stop 37 and force a metered quantity of fuel to be displacedand flow through delivery port 47 and conduit 55 and through injectionnozzle 22 connected to conduit 55. The metered quantity of fuel isdetermined by the axial position of the reciprocatable adjusting stopmember 38 which determines the stroke of shuttle 36.

In the next phase of the operation of distributor 20 the rotatablesleeve 35 rotates 45 from the position shown in the drawing to aposition where the port 78 in rotating sleeve 35 registers with deliveryport 51 and port 77 in sleeve 35 registers with inlet port 63. Whensleeve 35 is in this position the pressurized fuel in chamber 74 flowsthrough port 63 and forces shuttle 36 against adjustable stop 3% so asto displace and cause a metered quantity of fuel to flow throughdelivery port 51 and conduit 56 to an injection nozzle connected toconduit. in the further operation of distributor 20 shuttle 36 is causedto move back and forth between stops 37 and 38 as the ports 7'7 and 78in rotatable sleeve 35 alter nately become registered with feeder ports47 to 54 and delivery ports 63 to 75) during the rotation of rotatablesleeve 35.

The adjusting means of distributor 20 for varying the quantities of themetered charges delivered through conduits such as 55 and 56 toinjection nozzles connected thereto includes the reciprocatable stopmember 38 which is axially movable in rotatable sleeve 35. A spring 82is provided for biasing stop 38 to the left in a direction which reducesthe quantities of the metered charges. Stop 38 is provided with a rodextension 83 which. is used for.con-

trolling the position of stop 38 as will appear further on. Theinjection nozzles, one of which is shown, may be of any suitable type.Injection nozzle 22 illustrated herein is shown on the upstream side ofair intake valve but may be positioned to discharge directly into thecombustion chamber 13 if desired. Nozzle 22 comprises a valve 86 whichis biased to a closed position by a spring 87. When the spring loadedvalve 86 is subjected to pressure by pressurized fuel in conduit 55, thevalve opens to permit a metered quantity of fuel to be injected intocombustion chamber 13.

Control mechanism 23 functions to control the output of fuel distributor20 by actuating fuel distributor adjusting means which is illustratedherein as the linearly movable, piston shaped stop member 38. Controlmechanism 2-3 has an elongated casing 90 which is attached to andpositioned normal to fuel distributor 20. Mounted in casing 99 formovement longitudinally of casing 90 and normal to the longitudinal axisof distributor 20 is a linearly movable cone type of cam member 91having a generally conical portion which forms a camming profile. Thecamming profile of the conical portion of cam member 91 engages rod 83of adjustable stop member 38 for limiting the movement of stop member 38in accordance with engine conditions. The cumming profile is illustratedby way of example as having sections 93, 94-, 95 and 96 which are formedto correspond to coasting, idling, part throttle and full throttleconditions of the engine.

Cam member 91 has rod extensions at opposite ends thereof to facilitateactuation thereof. The lower part of casing 90 is formed with a fluidtight chamber 100 in which fluid pressure operable means such as abellows 101 is disposed. The lower rod of cam member 91 extends intochamber 166 and is attached to the top of bellows 101.

A conduit 132 is provided which extends between fluid tight chamber 100and air intake manifold 11 on the downstream side thereof from throttlevalve 15. Conduit 102 functions to communicate the pressure of the airflowing through the air intake manifold 11 to chamber 180 where thebellows 181 is linearly expanded and compressed in accordance with thispressure.

Bellows 101 is also actuated in accordance with the temperature of theair flowing in intake manifold 11 and for this function temperatureresponsive means are pro; vided which comprise a bulb 184 exposed to theinterior of air intake manifold 11 and a conduit which connects theinterior of bulb 104 to the interior of bellows 101. Bellows 101 isprovided with a suitable gas and the bellows will tend to expand andcontract in accordance with the rise and fall of the temperature of theair flowing in intake manifold 11.

The upper portion of casing 90 houses a spring 107 which is connected tothe upper rod extension of cam member 91. Spring 107 functions to biascam member 91 downwardly in a direction so that spring 187 transmits acompressing force to bellows 181.

In the operation of an engine having the control system, described, thethrottle valve 15 controls the air flowing to the engine and no othermanual controls are required. When cam member 91 is at a particularposition which corresponds to conditions in the air intake manifold 11the pressurized fuel'admitted alternately to opposite sides of shuttle36 causes movable stop member 38 to be forced to the right against thebiasing force of spring 82 into abutting engagement with cam member 91.The linear position of cam member 91 therefore de termines the distancemovable stop member is required to move to contact cam member 91 andconcomitantly determines the stroke of shuttle 36 and the quantities ofthe metered charges of fuel supplied to the engine by distributor 20. Ip

The cam member 91 has the profile of the conical portion thereof formedso that at various linear positions of the cam member the distributor 20will supply the engine with optimum amounts of fuel. The exactconfiguration for the profile of cam member 91 of course depends uponthe particular operating characteristics of an engine with which thecontrol system of the present invention is utilized. In general,however, the conical portion of the cam member 91 may have foursections.

Starting from the apex end of conical portion of cam member 91, section96 thereof contacts rod 83 of stop member 38 when throttle valve is in afull throttle position and the pressure of the resulting air flowthrough intake manifold is at a maximum value. The pressure from theintake manifold forces bellows 101 and cam member 91 in a downwardlydirection and in this position a maximum amount of fuel is injected intothe cylinders of the engine.

Section 95 of cam member 91 is for part throttle operation and givesmaximum economy. When throttle valve 15 is partly closed there is lesspressure in the air intake manifold 11 than at full throttle. Bellows101 is caused to expand relative to its full throttle position so thatsection 95 of the cam member abuts rod 83 movable stop member 38 andfunctions to control the stroke of shuttle 36.

Section 94 of cam member 91 is for idling operation and the relativelylarge manifold depression during idling causes bellows 101 to expandfurther relative to its part throttle position. Section 94 of the camthen abuts rod 83 of movable stop member 38 and only a relatively smallamount of fuel is supplied to the cylinders of the engine by distributor20.

Section 93 of cam member 91 is for coasting operation and functions tocut off entirely the fuel delivered by distributor to the engine. Duringcoasting the throttle valve 15 is closed and there is a relatively highair intake manifold depression. The high vacuum in the air intakemanifold causes a maximum amount of expansion of bellows 101 so thatsection 93 of cam member 91 contacts rod 83 of movable stop member 38.Cam section 93 is sufficiently flared so that it causes movement ofmovable stop 38 all the way to the left, against the pressure of thefuel supplied to distributor 20, so as to cause shuttle 36 to be trappedbetween stops 37 and 38. This prevents shuttle 36 from reciprocating andaccordingly no fuel is delivered by distributor 20 during the coastingoperation.

The control mechanism 23 is described above only with regard to itsoperation in accordance .with pressure variations in the air intakemanifold 11. The optimum fuel requirements of an engine also depend onthe temperature of the intake air. At a particular air intake manifolddepression more fuel will be required for cold air flowing in the intakemanifold than for warm air to maintain optimum air-fuel ratios. Thetemperature responsive means associated with bellows 101, which includesbulb 104 and conduit 105, functions to compensate for variations of theair intake temperatures. Temperatures increases and decreases of airflowing in air inlet manifold 11 tends to respectively expand andcontract the gas in bellows 101 and consequently tend to expand andcontract the bellows. Expansion of bellows 101 in the illustratedcontrol system effects a decrease in the fuel delivered by distributor20 and contraction of the bellows effects an increase in the fueldelivered.

The illustrated control mechanism 23 includes means for controlling cammember 91 thereof which is operative to air starting of an engine whenit is cold. "In'referring to a cold engine it is meant that the internaltemperature of the engine is below the normal operating temperature. Oneway in which the internal temperature of an engine may be obtained-orindicated is by placing temperature responsive means in the exhaustmanifold of the engine. The temperature of exhaust gases flowing throughthe exhaust manifold of an engine is a reliable indication of theinternal temperature of theengine and, as illustrated herein, abimetallic temperature responsive element 110. is mounted in an exhaustmanifold 111 of the engine;

Suitable means are provided which allows "bimetallic element to dominatethe control of cam member 91 during the time an engine is being warmedfrom a'cold condition to a predetermined temperature and then"completely relinquishes control of cam member 91. This mechanismincludes a camf112fpivotally mounted in the upper portion of casing '90whichis connected to bimetallic element 110 by a link 113 which causescam .112 to pivot in response to expanding and contracting movements ofelement 110. Cam112 has a follower 114 which has a flange in abuttingengagement with spring 107. Cam 112 moves adjustable upper springabutment 114 downward compressing spring 107 when bimetallic element 110is contracted due to the engine being'col'd. The additional compressionof spring 107 opposes the upward force exerted by bellows 101 beyond"its normal value, causing an enrichment of "the fuel-air mixture asrequired by a cold engine. As the engine war-ms up, 'bimetallic element110 expands and causes cam 1'12 to gradually rotate until the pressureof "spring 107 returns to its normal value as set by the adjustmentscrew of upper spring abutment 114 with a warm engine. Control of cammember '91 is then taken over by bellows .101'as described above.

The invention may be embodied in other specific form-s without departingfrom the spirit or essential character istics thereof. The presentembodiment of the invention is therefore to be considered in allrespects as illustrative and not restrictive, the scope of the inventionbeing indicated by the appended claimsrather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embracedztherein.

It is claimed and desired to secure by Letters Patent:

1. A fuel control system for an internal combustion engine having an airintake manifold, an exhaust manifold, and throttle means for varying'theflow of air through the air intake manifold, .said system comprisingliquid fuel pumping means, an engine driven liquid fuel distributoradapted to receive liquid fuel under pressure from said pumping meansand effect the delivery of metered charges of the fuel to the combustioncham'bers of the engine, said distributor including metering ad'-justing means for varying the quantities of the metered charges, cammeans mounted for linear movement to efliect positioning of saidmetering adjusting means corresponding to linear positions of the cammeans, means responsive to engine conditions including the internaltemperature of the engine and the temperature and pressure of air.flowing in said engine intake manifold on the downstream side of saidthrottle to effect linear movement of said cam means, said cam meanshaving .a profile forrned to effect movement of said metering adjustingmeans to positions corresponding to engine conditions upon linearmovement of the cam means.

2. A fuel control system for an internal combustion engine having an airintake manifold, an exhaust manifold, and throttle means for varying theflow of tail through the air intake manifold, said system comprisingliquid fuel pumping means, an engine .driven liquid fuel distributoradapted to receive liquid fuel under pressure from said pumping meansand effect the delivery of metered charges of the fuel to the combustionchambers of the engine, said distributor including reciprocata b'lemetering adjusting means .for varying the quantities of the meteredcharges, cam :means mounted for linear movement to effect positioning:of said metering adjusting means corresponding to linear positions ofthe cam means, means responsive 'to engine conditions including theinternal temperature of the engine and the temperature and pressure ofair flowing 'in said engine intake manifold on the downstream side ofsaid throttle to effect linear movement of said cam means, said cammeans having'a profile formed to effect movement of said meteringadjusting means to positions corresponding to engine conditions uponlinear movement 'of the cam means, and means responsive to internalengine temperature operably connected to said cam means for dominatingthe control of said cam means when the temperature of said engine isbelow the normal operating temperature, said means responsive tointernal engine temperature being effective to move said cam means to aposition corresponding to the delivery of maximum quantities of meteredfuel charges by said distributor when the temperature of said engine issubstantially below normal operating temperature and to graduallyrelinquish control of said cam means as the normal operating temperatureof said engine is approached.

3. A fuel control system for an internal combustion engine having an airintake manifold, an exhaust manifold, and throttle means for varying theflow of air through the air intake manifold, said system comprisingliquid fuel pumping means, an engine driven liquid fuel distributoradapted to receive liquid fuel under pressure from said pumping meansand effect the delivery of metered charges of the fuel to the combustionchambers of the engine, said distributorincluding metering adjustingmeans for varying the quantities of the metered charges, cam meansmounted for linear movement to effect positioning of said meteringadjusting means corresponding to linear position of the cam means, fluidpressure operable means operably connected to said cam means to effectlinear movement of said cam means in opposite directions to increase anddecrease the quantities of the metered charges when said'fluid pressureoperable means is respectively contracted and expanded, conduit meansconnecting said fluid pressure operable means to the interior of saidintake manifold downstream from said throttle means to effectcontraction and expansion of said fluid pressure operable means inaccordance with pressure variations in said intake manifold, temperatureresponsive means exposed to the air flowing in said intake manifoldoperably connected to said fluid pressure operable means to effectexpansion and contraction of said fluid pressure operable means inaccordance with the temperature of the air flowing in said intakemanifold, said cam means having a profile formed to effect movement ofsaid metering adjusting means to optimum positions corresponding toengine conditions upon linear movement of said first cam means.

4. A fuel control system for an internal combustion engine having an airintake manifold, an exhaust manifold, and throttle means for varying theflow of air through the air intake manifold, said system comprisingliquid fuel pumping means, an engine driven liquid fuel distributoradapted to receive liquid fuel under pressure from said pumping meansand efiect the delivery of metered charges of the fuel to the combustionchambers of the engine, said distributor including metering adjustingmeans for varying the quantities of the metered charges, cam meansmounted for linear movement to effect positioning of said meteringadjusting means corresponding to linear positions of the cam means,fluid pressure operable means operably connected to said cam means toeffect linear movement of said cam means in opposite directions toincrease and decrease the quantities of the metered charges when saidfluid pressure operable means is respectively contracted and expanded,conduit means connecting said fluid pressure operable means to theinterior of said intake manifold downstream from said throttle means toeffect contraction and expansion of said fluid pressure operable meansin accordance with pressure variations in said intake manifold,temperature responsive'means exposed to the air flowing in said intakemanifold operably connected to said fluid pressure operable means toeffect expansion and contraction of said fluid pressure operable meansin accordance with the temperature of the air flowing in said intakemanifold, means operably connected to said cam means which dominates thecontrol of said cam means when the temperature of said engine is belowthe normal operating temperature, means responsive to the internaltemperature operably connected to said cam means to effect movement ofsaid cam means to a position corresponding to the delivery of maximumquantities of metered fuel charges by said distributor when thetemperature of said engine is substantially below normal operatingtemperature and to gradually relinquish control of said cam means as thenormal operating temperature of said engine is approached, said cammeans having a profile formed to effect movement of said meteringadjusting means to optimum positions corresponding to engine conditionsupon linear movement of said-first cam means.

5. A fuel control system for an internal combustion engine having an airintake manifold, an exhaust manifold, and throttle means for varying theflow of air through the air intake manifold, said system comprisingliquid fuel pumping means, an engine driven liquid fuel distributoradapted to receive liquid fuel under pressure from said pumping meansand effect the delivery of metered charges of the fuel to the combustionchambers of the engine, said distributor including reciprocatablemetering adjusting means for varying the quantities of the meteredcharges, first cam means mounted for linear movement to effectpositioning of said metering adjusting means corresponding to linearpositions of the cam means, a bellows operably connected to said firstcam means to effect linear movement of said first cam means in oppositedirections to increase and decrease the quantities of the meteredcharges when said bellows is respectively' contracted and expanded, afluid tight casing surrounding said bellows, conduit means connectingthe interior of said casing to the interior of said intake manifolddownstream from said throttle means to vary the external pressure onsaid bellows to effect contraction and expansion of the bellows inaccordance with pressure variations in said intake manifold, temperatureresponsive means including a hollow bulb having the exterior of the bulbexposed to the air flowing in said intake manifold and the interior ofsaid bulb in communication with the interior of said bulb to effectexpansion and contraction of said bellows in accordance with the temperature of the air flowing in said intake manifold, second cam meansoperably connected to said first cam means which dominates the controlof said first cam means when the temperature of said engine is below thenormal operating temperature, resilient means operably disposed betweensaid second cam means and said first cam means, a temperature responsivebimetallic strip disposed in the exhaust manifold of said engine andoperably connected to said second cam means to effect movement of saidfirst cam means to a position corresponding to the delivery of maximumquantities of metered fuel charges by said distributor when thetemperature of said engine is substantially below normal operatingtemperature and to gradually relinquish control of said first cam meansas the normal operating temperature of said engine is approached, saidfirst cam means having a profile formed to effect movement of saidmetering adjusting means to optimum positions corresponding to engineconditions of coating, idling, part throttle and full throttle uponlinear movement of said first cam means.

6. A fuel control system for an internal combustion engine having an airintake manifold an exhaust manifold, and throttle means for varying theflow of air through the air intake manifold, said system comprising ofthe engine, said distributor including reciprocatable metering adjustingmeans for varying the quantities of the metered charges, first resilientmeans biasing said metering adjusting means towards a closed position,first cam means mounted for linear movement to effect positioning ofsaid metering adjusting means corresponding to linear positions of thecam means, a bellows operably connected to said first cam means toelfect linear movement of said first cam means in opposite directions toincrease and decrease the quantities of the metered charges when saidbellows is respectively contracted and expanded, second resilient meansbiasing said first cam means in a direction towards decreasing thequantities of the metered charges, a fluid tight casing surrounding saidbellows, conduit means connecting the interior of said casing to theinterior-of said intake manifold downstream from said throttle means tovary the external pressure on said bellows to effect contraction andexpansion of the bellows in accordance with pressure variations in saidintake manifold, temperature responsive means including a hollow bulbhaving the exterior of the bulb exposed to the air flowing in saidintake manifold and the interior of said bulb in communication with theinterior of said bulb to efiect expansion and contraction of saidbellows in accordance with the temperature of the air flowing in saidintake manifold, second cam means operably connected to said first cammeans which dominates the control of said first cam means When thetemperature of said engine is below the normal operating temperature,said second resilient means being operably disposed between said secondcam means and said first cam means, a temperature responsive bimetallicstrip disposed in the exhaust manifold of said engine and operablyconnected to said second cam means to effect move ment of said first cammeans to a position corresponding to the delivery of maximum quantitiesof metered fuel charges by said distributor when the temperature of saidengine is substantially below normal operating temperature and togradually relinquish control of said first cam means as the normaloperating temperature of said engine is approached, said first cam meanshaving a profile formed to effect movement of said metering adjustingmeans to optimum positions corresponding to engine conditions ofcoasting, idling, part throttle and full throttle upon linear movementof said first cam means.

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